# -*- coding: utf-8 -*-
# Copyright (C) 2012 Anaconda, Inc
# SPDX-License-Identifier: BSD-3-Clause
from __future__ import absolute_import, division, print_function, unicode_literals

from abc import ABCMeta, abstractmethod, abstractproperty
from errno import EXDEV
from logging import getLogger
from os.path import basename, dirname, getsize, join
import re
from uuid import uuid4

from .envs_manager import USER_ENVIRONMENTS_TXT_FILE, register_env, unregister_env
from .portability import _PaddingError, update_prefix
from .prefix_data import PrefixData
from .._vendor.auxlib.compat import with_metaclass
from .._vendor.auxlib.ish import dals
from ..base.constants import CONDA_TARBALL_EXTENSION
from ..base.context import context
from ..common.compat import iteritems, on_win, text_type
from ..common.path import (get_bin_directory_short_path, get_leaf_directories,
                           get_python_noarch_target_path, get_python_short_path,
                           parse_entry_point_def,
                           pyc_path, url_to_path, win_path_ok)
from ..common.url import has_platform, path_to_url, unquote
from ..exceptions import CondaUpgradeError, CondaVerificationError, PaddingError, SafetyError
from ..gateways.connection.download import download
from ..gateways.disk.create import (compile_pyc, copy, create_hard_link_or_copy,
                                    create_link, create_python_entry_point, extract_tarball,
                                    make_menu, write_as_json_to_file)
from ..gateways.disk.delete import rm_rf, try_rmdir_all_empty
from ..gateways.disk.permissions import make_writable
from ..gateways.disk.read import (compute_md5sum, compute_sha256sum, islink, lexists,
                                  read_index_json)
from ..gateways.disk.update import backoff_rename, touch
from ..history import History
from ..models.channel import Channel
from ..models.enums import LinkType, NoarchType, PathType
from ..models.match_spec import MatchSpec
from ..models.records import (Link, PackageCacheRecord, PackageRecord, PathDataV1, PathsData,
                              PrefixRecord)

try:
    from cytoolz.itertoolz import concat, concatv
except ImportError:  # pragma: no cover
    from .._vendor.toolz.itertoolz import concat, concatv  # NOQA

log = getLogger(__name__)

REPR_IGNORE_KWARGS = (
    'transaction_context',
    'package_info',
    'hold_path',
)


@with_metaclass(ABCMeta)
class PathAction(object):

    _verified = False

    @abstractmethod
    def verify(self):
        # if verify fails, it should return an exception object rather than raise
        #  at the end of a verification run, all errors will be raised as a CondaMultiError
        # after successful verification, the verify method should set self._verified = True
        raise NotImplementedError()

    @abstractmethod
    def execute(self):
        raise NotImplementedError()

    @abstractmethod
    def reverse(self):
        raise NotImplementedError()

    @abstractmethod
    def cleanup(self):
        raise NotImplementedError()

    @abstractproperty
    def target_full_path(self):
        raise NotImplementedError()

    @property
    def verified(self):
        return self._verified

    def __repr__(self):
        args = ('%s=%r' % (key, value) for key, value in iteritems(vars(self))
                if key not in REPR_IGNORE_KWARGS)
        return "%s(%s)" % (self.__class__.__name__, ', '.join(args))


@with_metaclass(ABCMeta)
class PrefixPathAction(PathAction):

    def __init__(self, transaction_context, target_prefix, target_short_path):
        self.transaction_context = transaction_context
        self.target_prefix = target_prefix
        self.target_short_path = target_short_path

    @property
    def target_full_path(self):
        trgt, shrt_pth = self.target_prefix, self.target_short_path
        if trgt is not None and shrt_pth is not None:
            return join(trgt, win_path_ok(shrt_pth))
        else:
            return None


# ######################################################
#  Creation of Paths within a Prefix
# ######################################################

@with_metaclass(ABCMeta)
class CreateInPrefixPathAction(PrefixPathAction):
    # All CreatePathAction subclasses must create a SINGLE new path
    #   the short/in-prefix version of that path must be returned by execute()

    def __init__(self, transaction_context, package_info, source_prefix, source_short_path,
                 target_prefix, target_short_path):
        super(CreateInPrefixPathAction, self).__init__(transaction_context,
                                                       target_prefix, target_short_path)
        self.package_info = package_info
        self.source_prefix = source_prefix
        self.source_short_path = source_short_path

    def verify(self):
        self._verified = True

    def cleanup(self):
        # create actions typically won't need cleanup
        pass

    @property
    def source_full_path(self):
        prfx, shrt_pth = self.source_prefix, self.source_short_path
        return join(prfx, win_path_ok(shrt_pth)) if prfx and shrt_pth else None


class LinkPathAction(CreateInPrefixPathAction):

    @classmethod
    def create_file_link_actions(cls, transaction_context, package_info, target_prefix,
                                 requested_link_type):
        def get_prefix_replace(source_path_data):
            if source_path_data.path_type == PathType.softlink:
                link_type = LinkType.copy
                prefix_placehoder, file_mode = '', None
            elif source_path_data.prefix_placeholder:
                link_type = LinkType.copy
                prefix_placehoder = source_path_data.prefix_placeholder
                file_mode = source_path_data.file_mode
            elif source_path_data.no_link:
                link_type = LinkType.copy
                prefix_placehoder, file_mode = '', None
            else:
                link_type = requested_link_type
                prefix_placehoder, file_mode = '', None

            return link_type, prefix_placehoder, file_mode

        def make_file_link_action(source_path_data):
            # TODO: this inner function is still kind of a mess
            noarch = package_info.repodata_record.noarch
            if noarch == NoarchType.python:
                sp_dir = transaction_context['target_site_packages_short_path']
                target_short_path = get_python_noarch_target_path(source_path_data.path, sp_dir)
            elif noarch is None or noarch == NoarchType.generic:
                target_short_path = source_path_data.path
            else:
                raise CondaUpgradeError(dals("""
                The current version of conda is too old to install this package.
                Please update conda."""))

            link_type, placeholder, fmode = get_prefix_replace(source_path_data)

            if placeholder:
                return PrefixReplaceLinkAction(transaction_context, package_info,
                                               package_info.extracted_package_dir,
                                               source_path_data.path,
                                               target_prefix, target_short_path,
                                               requested_link_type,
                                               placeholder, fmode, source_path_data)
            else:
                return LinkPathAction(transaction_context, package_info,
                                      package_info.extracted_package_dir, source_path_data.path,
                                      target_prefix, target_short_path,
                                      link_type, source_path_data)
        return tuple(make_file_link_action(spi) for spi in package_info.paths_data.paths)

    @classmethod
    def create_directory_actions(cls, transaction_context, package_info, target_prefix,
                                 requested_link_type, file_link_actions):
        leaf_directories = get_leaf_directories(axn.target_short_path for axn in file_link_actions)
        return tuple(
            cls(transaction_context, package_info, None, None,
                target_prefix, directory_short_path, LinkType.directory, None)
            for directory_short_path in leaf_directories
        )

    @classmethod
    def create_python_entry_point_windows_exe_action(cls, transaction_context, package_info,
                                                     target_prefix, requested_link_type,
                                                     entry_point_def):
        source_directory = context.conda_prefix
        source_short_path = 'Scripts/conda.exe'
        command, _, _ = parse_entry_point_def(entry_point_def)
        target_short_path = "Scripts/%s.exe" % command
        source_path_data = PathDataV1(
            _path=target_short_path,
            path_type=PathType.windows_python_entry_point_exe,
        )
        return cls(transaction_context, package_info, source_directory,
                   source_short_path, target_prefix, target_short_path,
                   requested_link_type, source_path_data)

    def __init__(self, transaction_context, package_info,
                 extracted_package_dir, source_short_path,
                 target_prefix, target_short_path, link_type, source_path_data):
        super(LinkPathAction, self).__init__(transaction_context, package_info,
                                             extracted_package_dir, source_short_path,
                                             target_prefix, target_short_path)
        self.link_type = link_type
        self._execute_successful = False
        self.source_path_data = source_path_data
        self.prefix_path_data = None

    def verify(self):
        if self.link_type != LinkType.directory and not lexists(self.source_full_path):  # pragma: no cover  # NOQA
            return CondaVerificationError(dals("""
            The package for %s located at %s
            appears to be corrupted. The path '%s'
            specified in the package manifest cannot be found.
            """ % (self.package_info.repodata_record.name,
                   self.package_info.extracted_package_dir,
                   self.source_short_path)))

        source_path_data = self.source_path_data
        try:
            source_path_type = source_path_data.path_type
        except AttributeError:
            source_path_type = None
        if source_path_type in PathType.basic_types:
            # this let's us keep the non-generic path types like windows_python_entry_point_exe
            source_path_type = None

        if self.link_type == LinkType.directory:
            self.prefix_path_data = None
        elif self.link_type == LinkType.softlink:
            self.prefix_path_data = PathDataV1.from_objects(
                self.source_path_data,
                path_type=source_path_type or PathType.softlink,
            )
        elif self.link_type == LinkType.copy and source_path_data.path_type == PathType.softlink:
            self.prefix_path_data = PathDataV1.from_objects(
                self.source_path_data,
                path_type=source_path_type or PathType.softlink,
            )

        elif source_path_data.path_type == PathType.hardlink:
            try:
                reported_sha256 = source_path_data.sha256
            except AttributeError:
                reported_sha256 = None
            source_sha256 = compute_sha256sum(self.source_full_path)
            if reported_sha256 and reported_sha256 != source_sha256:
                return SafetyError(dals("""
                The package for %s located at %s
                appears to be corrupted. The path '%s'
                has a sha256 mismatch.
                  reported sha256: %s
                  actual sha256: %s
                """ % (self.package_info.repodata_record.name,
                       self.package_info.extracted_package_dir,
                       self.source_short_path,
                       reported_sha256,
                       source_sha256,
                       )))

            try:
                reported_size_in_bytes = source_path_data.size_in_bytes
            except AttributeError:
                reported_size_in_bytes = None
            if reported_size_in_bytes:
                source_size_in_bytes = getsize(self.source_full_path)
                if reported_size_in_bytes != source_size_in_bytes:
                    return SafetyError(dals("""
                    The package for %s located at %s
                    appears to be corrupted. The path '%s'
                    has an incorrect size.
                      reported size: %s bytes
                      actual size: %s bytes
                    """ % (self.package_info.repodata_record.name,
                           self.package_info.extracted_package_dir,
                           self.source_short_path,
                           reported_size_in_bytes,
                           source_size_in_bytes,
                           )))

            self.prefix_path_data = PathDataV1.from_objects(
                source_path_data,
                sha256=reported_sha256,
                sha256_in_prefix=reported_sha256,
                path_type=source_path_type or PathType.hardlink,
            )
        elif source_path_data.path_type == PathType.windows_python_entry_point_exe:
            self.prefix_path_data = source_path_data
        else:
            raise NotImplementedError()

        self._verified = True

    def execute(self):
        log.trace("linking %s => %s", self.source_full_path, self.target_full_path)
        create_link(self.source_full_path, self.target_full_path, self.link_type,
                    force=context.force)
        self._execute_successful = True

    def reverse(self):
        if self._execute_successful:
            log.trace("reversing link creation %s", self.target_prefix)
            if self.link_type == LinkType.directory:
                try_rmdir_all_empty(self.target_full_path)
            else:
                rm_rf(self.target_full_path)


class PrefixReplaceLinkAction(LinkPathAction):

    def __init__(self, transaction_context, package_info,
                 extracted_package_dir, source_short_path,
                 target_prefix, target_short_path,
                 link_type,
                 prefix_placeholder, file_mode, source_path_data):
        # This link_type used in execute(). Make sure we always respect LinkType.copy request.
        link_type = LinkType.copy if link_type == LinkType.copy else LinkType.hardlink
        super(PrefixReplaceLinkAction, self).__init__(transaction_context, package_info,
                                                      extracted_package_dir, source_short_path,
                                                      target_prefix, target_short_path,
                                                      link_type, source_path_data)
        self.prefix_placeholder = prefix_placeholder
        self.file_mode = file_mode
        self.intermediate_path = None

    def verify(self):
        validation_error = super(PrefixReplaceLinkAction, self).verify()
        if validation_error:
            return validation_error

        if islink(self.source_full_path):
            log.trace("ignoring prefix update for symlink with source path %s",
                      self.source_full_path)
            # return
            assert False, "I don't think this is the right place to ignore this"

        self.intermediate_path = join(self.transaction_context['temp_dir'], text_type(uuid4()))

        log.trace("copying %s => %s", self.source_full_path, self.intermediate_path)
        create_link(self.source_full_path, self.intermediate_path, LinkType.copy)
        make_writable(self.intermediate_path)

        try:
            log.trace("rewriting prefixes in %s", self.target_full_path)
            update_prefix(self.intermediate_path,
                          context.target_prefix_override or self.target_prefix,
                          self.prefix_placeholder,
                          self.file_mode)
        except _PaddingError:
            raise PaddingError(self.target_full_path, self.prefix_placeholder,
                               len(self.prefix_placeholder))

        sha256_in_prefix = compute_sha256sum(self.intermediate_path)

        self.prefix_path_data = PathDataV1.from_objects(
            self.prefix_path_data,
            file_mode=self.file_mode,
            path_type=PathType.hardlink,
            prefix_placeholder=self.prefix_placeholder,
            sha256_in_prefix=sha256_in_prefix,
        )

        self._verified = True

    def execute(self):
        if not self._verified:
            self.verify()
        source_path = self.intermediate_path or self.source_full_path
        log.trace("linking %s => %s", source_path, self.target_full_path)
        create_link(source_path, self.target_full_path, self.link_type)
        self._execute_successful = True


class MakeMenuAction(CreateInPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type):
        if on_win and context.shortcuts:
            MENU_RE = re.compile(r'^menu/.*\.json$', re.IGNORECASE)
            return tuple(cls(transaction_context, package_info, target_prefix, spi.path)
                         for spi in package_info.paths_data.paths if bool(MENU_RE.match(spi.path)))
        else:
            return ()

    def __init__(self, transaction_context, package_info, target_prefix, target_short_path):
        super(MakeMenuAction, self).__init__(transaction_context, package_info,
                                             None, None, target_prefix, target_short_path)
        self._execute_successful = False

    def execute(self):
        log.trace("making menu for %s", self.target_full_path)
        make_menu(self.target_prefix, self.target_short_path, remove=False)
        self._execute_successful = True

    def reverse(self):
        if self._execute_successful:
            log.trace("removing menu for %s", self.target_full_path)
            make_menu(self.target_prefix, self.target_short_path, remove=True)


class CreateNonadminAction(CreateInPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type):
        if on_win and lexists(join(context.root_prefix, '.nonadmin')):
            return cls(transaction_context, package_info, target_prefix),
        else:
            return ()

    def __init__(self, transaction_context, package_info, target_prefix):
        super(CreateNonadminAction, self).__init__(transaction_context, package_info, None, None,
                                                   target_prefix, '.nonadmin')
        self._file_created = False

    def execute(self):
        log.trace("touching nonadmin %s", self.target_full_path)
        self._file_created = touch(self.target_full_path)

    def reverse(self):
        if self._file_created:
            log.trace("removing nonadmin file %s", self.target_full_path)
            rm_rf(self.target_full_path)


class CompilePycAction(CreateInPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type,
                       file_link_actions):
        noarch = package_info.package_metadata and package_info.package_metadata.noarch
        if noarch is not None and noarch.type == NoarchType.python:
            noarch_py_file_re = re.compile(r'^site-packages[/\\][^\t\n\r\f\v]+\.py$')
            py_ver = transaction_context['target_python_version']
            py_files = (axn.target_short_path for axn in file_link_actions
                        if noarch_py_file_re.match(axn.source_short_path))
            return tuple(cls(transaction_context, package_info, target_prefix,
                             pf, pyc_path(pf, py_ver))
                         for pf in py_files)
        else:
            return ()

    def __init__(self, transaction_context, package_info, target_prefix,
                 source_short_path, target_short_path):
        super(CompilePycAction, self).__init__(transaction_context, package_info,
                                               target_prefix, source_short_path,
                                               target_prefix, target_short_path)
        self.prefix_path_data = PathDataV1(
            _path=self.target_short_path,
            path_type=PathType.pyc_file,
        )
        self._execute_successful = False

    def execute(self):
        # compile_pyc is sometimes expected to fail, for example a python 3.6 file
        #   installed into a python 2 environment, but no code paths actually importing it
        # technically then, this file should be removed from the manifest in conda-meta, but
        #   at the time of this writing that's not currently happening
        log.trace("compiling %s", self.target_full_path)
        target_python_version = self.transaction_context['target_python_version']
        python_short_path = get_python_short_path(target_python_version)
        python_full_path = join(self.target_prefix, win_path_ok(python_short_path))
        compile_pyc(python_full_path, self.source_full_path, self.target_full_path)
        self._execute_successful = True

    def reverse(self):
        if self._execute_successful:
            log.trace("reversing pyc creation %s", self.target_full_path)
            rm_rf(self.target_full_path)


class CreatePythonEntryPointAction(CreateInPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type):
        noarch = package_info.package_metadata and package_info.package_metadata.noarch
        if noarch is not None and noarch.type == NoarchType.python:
            def this_triplet(entry_point_def):
                command, module, func = parse_entry_point_def(entry_point_def)
                target_short_path = "%s/%s" % (get_bin_directory_short_path(), command)
                if on_win:
                    target_short_path += "-script.py"
                return target_short_path, module, func

            actions = tuple(cls(transaction_context, package_info, target_prefix,
                                *this_triplet(ep_def))
                            for ep_def in noarch.entry_points or ())

            if on_win:  # pragma: unix no cover
                actions += tuple(
                    LinkPathAction.create_python_entry_point_windows_exe_action(
                        transaction_context, package_info, target_prefix,
                        requested_link_type, ep_def
                    ) for ep_def in noarch.entry_points or ()
                )

            return actions
        else:
            return ()

    def __init__(self, transaction_context, package_info, target_prefix, target_short_path,
                 module, func):
        super(CreatePythonEntryPointAction, self).__init__(transaction_context, package_info,
                                                           None, None,
                                                           target_prefix, target_short_path)
        self.module = module
        self.func = func

        if on_win:
            path_type = PathType.windows_python_entry_point_script
        else:
            path_type = PathType.unix_python_entry_point
        self.prefix_path_data = PathDataV1(
            _path=self.target_short_path,
            path_type=path_type,
        )

        self._execute_successful = False

    def execute(self):
        log.trace("creating python entry point %s", self.target_full_path)
        if on_win:
            python_full_path = None
        else:
            target_python_version = self.transaction_context['target_python_version']
            python_short_path = get_python_short_path(target_python_version)
            python_full_path = join(self.target_prefix, win_path_ok(python_short_path))

        create_python_entry_point(self.target_full_path, python_full_path,
                                  self.module, self.func)
        self._execute_successful = True

    def reverse(self):
        if self._execute_successful:
            log.trace("reversing python entry point creation %s", self.target_full_path)
            rm_rf(self.target_full_path)


# class CreateApplicationEntryPointWindowsExeAction(LinkPathAction):
#
#     @classmethod
#     def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type,  # NOQA
#                        exe_path):
#         source_directory = context.conda_prefix
#         source_short_path = 'Scripts/conda.exe'
#         target_short_path = exe_path
#         return cls(transaction_context, package_info, source_directory,
#                    source_short_path, target_prefix, target_short_path, requested_link_type)
#
#     def __init__(self, transaction_context, package_info, source_prefix, source_short_path,
#                  target_prefix, target_short_path, requested_link_type):
#         super(CreateApplicationEntryPointWindowsExeAction, self).__init__(
#             transaction_context, package_info, source_prefix, source_short_path,
#             target_prefix, target_short_path, requested_link_type,
#         )
#         self.leased_path_entry = LeasedPathEntry(
#             _path=target_short_path,
#             target_path=self.source_full_path,
#             target_prefix=source_prefix,
#             leased_path=self.target_full_path,
#             package_name=package_info.index_json_record.name,
#             leased_path_type=self.leased_path_type,
#         )
#
#     @property
#     def leased_path_type(self):
#         return LeasedPathType.application_entry_point_windows_exe


# class CreateApplicationEntryPointAction(CreateLeasedPathAction):
#
#     @classmethod
#     def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type):  # NOQA
#         preferred_env = package_info.repodata_record.preferred_env
#         if preferred_env_matches_prefix(preferred_env, target_prefix, context.root_prefix):
#             exe_paths = (package_info.package_metadata
#                          and package_info.package_metadata.preferred_env
#                          and package_info.package_metadata.preferred_env.executable_paths
#                          or ())
#
#             # target_prefix for the instantiated path action is the root prefix, not the same
#             #   as target_prefix for the larger transaction
#             assert is_private_env_path(target_prefix)
#             root_prefix = dirname(dirname(target_prefix))
#
#             if on_win:
#                 def make_app_entry_point_axns(exe_path):
#                     assert exe_path.endswith(('.exe', '.bat'))
#                     target_short_path = exe_path[:-4] + "-script.py"
#                     yield cls(transaction_context, package_info, target_prefix, exe_path,
#                               root_prefix, target_short_path)
#
#                     yield CreateApplicationEntryPointWindowsExeAction.create_actions(
#                         transaction_context, package_info, root_prefix,
#                         LinkType.hardlink, exe_path[:-4] + ".exe"
#                     )
#                 return tuple(concat(make_app_entry_point_axns(executable_short_path)
#                                     for executable_short_path in exe_paths))
#
#             else:
#                 return tuple(
#                     cls(transaction_context, package_info, target_prefix, executable_short_path,
#                         root_prefix, executable_short_path)
#                     for executable_short_path in exe_paths
#                 )
#         else:
#             return ()
#
#     def execute(self):
#         log.trace("creating application entry point %s => %s",
#                   self.source_full_path, self.target_full_path)
#         if self.source_prefix == context.conda_prefix:
#             # this could blow up for the special case of application entry points in conda's
#             #   private environment
#             # in that case, probably should use the python version from transaction_context
#             conda_python_version = self.transaction_context['target_python_version']
#         else:
#             conda_python_version = get_python_version_for_prefix(context.conda_prefix)
#         conda_python_short_path = get_python_short_path(conda_python_version)
#         conda_python_full_path = join(context.conda_prefix, win_path_ok(conda_python_short_path))
#         create_application_entry_point(self.source_full_path, self.target_full_path,
#                                        conda_python_full_path)
#         self._execute_successful = True
#
#     @property
#     def leased_path_type(self):
#         return LeasedPathType.application_entry_point
#
#
# class CreateApplicationSoftlinkAction(CreateLeasedPathAction):
#
#     @classmethod
#     def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type):  # NOQA
#         preferred_env = package_info.repodata_record.preferred_env
#         if preferred_env_matches_prefix(preferred_env, target_prefix, context.root_prefix):
#             softlink_paths = (package_info.package_metadata
#                               and package_info.package_metadata.preferred_env
#                               and package_info.package_metadata.preferred_env.softlink_paths
#                               or ())
#
#             # target_prefix for the instantiated path action is the root prefix, not the same
#             #   as target_prefix for the larger transaction
#             assert is_private_env_path(target_prefix)
#             root_prefix = dirname(dirname(target_prefix))
#             softlink_supported_test_file = join(target_prefix, PREFIX_MAGIC_FILE)
#
#             def make_softlink_exe_axn(softlink_short_path):
#                 if not on_win:  # pragma: win no cover
#                     root_short_path = softlink_short_path
#                     softlink_method = 'softlink'
#                 else:  # pragma: unix no cover
#                     windows_pathext = os.getenv('PATHEXT', '').lower().split(';')
#                     path_root, path_ext = splitext(softlink_short_path)
#
#                     if softlink_supported(softlink_supported_test_file, root_prefix):
#                         root_short_path = softlink_short_path
#                         softlink_method = 'softlink'
#                     elif path_ext.lower() in windows_pathext:
#                         root_short_path = splitext(softlink_short_path)[0] + '.bat'
#                         softlink_method = 'fake_exe_softlink'
#                     else:
#                         root_short_path = softlink_short_path
#                         softlink_method = 'softlink_or_fail_ok'
#
#                 return cls(transaction_context, package_info, target_prefix, softlink_short_path,
#                            root_prefix, root_short_path, softlink_method)
#
#             return tuple(make_softlink_exe_axn(softlink_short_path)
#                          for softlink_short_path in softlink_paths)
#
#         else:
#             return ()
#
#     def __init__(self, transaction_context, package_info, source_prefix, source_short_path,
#                  target_prefix, target_short_path, softlink_method):
#         super(CreateApplicationSoftlinkAction, self).__init__(transaction_context, package_info,
#                                                               source_prefix, source_short_path,
#                                                               target_prefix, target_short_path)
#         self.softlink_method = softlink_method
#
#     def execute(self):
#         log.trace("creating application softlink via %s %s => %s",
#                   self.softlink_method, self.source_full_path, self.target_full_path)
#         getattr(self, self.softlink_method)()
#         self._execute_successful = True
#
#     def softlink(self):
#         symlink(self.source_full_path, self.target_full_path)
#         assert islink(self.target_full_path)
#
#     def fake_exe_softlink(self):  # pragma: unix no cover
#         create_fake_executable_softlink(self.source_full_path, self.target_full_path)
#
#     def softlink_or_fail_ok(self):  # pragma: unix no cover
#         try:
#             symlink(self.source_full_path, self.target_full_path)
#         except (IOError, OSError) as e:
#             log.trace('%r', e)
#
#     @property
#     def leased_path_type(self):
#         return LeasedPathType.application_softlink


class CreatePrefixRecordAction(CreateInPrefixPathAction):
    # this is the action that creates a packages json file in the conda-meta/ directory

    @classmethod
    def create_actions(cls, transaction_context, package_info, target_prefix, requested_link_type,
                       requested_spec, all_link_path_actions):

        extracted_package_dir = package_info.extracted_package_dir
        target_short_path = 'conda-meta/%s.json' % basename(extracted_package_dir)
        return cls(transaction_context, package_info, target_prefix, target_short_path,
                   requested_link_type, requested_spec, all_link_path_actions),

    def __init__(self, transaction_context, package_info, target_prefix, target_short_path,
                 requested_link_type, requested_spec, all_link_path_actions):
        super(CreatePrefixRecordAction, self).__init__(transaction_context, package_info,
                                                       None, None, target_prefix,
                                                       target_short_path)
        self.requested_link_type = requested_link_type
        self.requested_spec = requested_spec
        self.all_link_path_actions = all_link_path_actions

    def execute(self):
        link = Link(
            source=self.package_info.extracted_package_dir,
            type=self.requested_link_type,
        )
        extracted_package_dir = self.package_info.extracted_package_dir
        package_tarball_full_path = extracted_package_dir + CONDA_TARBALL_EXTENSION
        # TODO: don't make above assumption; put package_tarball_full_path in package_info

        files = (x.target_short_path for x in self.all_link_path_actions if x)

        paths_data = PathsData(
            paths_version=1,
            paths=(x.prefix_path_data for x in self.all_link_path_actions
                   if x and x.prefix_path_data),
        )

        self.prefix_record = PrefixRecord.from_objects(
            self.package_info.repodata_record,
            # self.package_info.index_json_record,
            self.package_info.package_metadata,
            requested_spec=text_type(self.requested_spec),
            paths_data=paths_data,
            files=files,
            link=link,
            url=self.package_info.url,
            extracted_package_dir=extracted_package_dir,
            package_tarball_full_path=package_tarball_full_path,
        )

        log.trace("creating linked package record %s", self.target_full_path)
        PrefixData(self.target_prefix).insert(self.prefix_record)

    def reverse(self):
        log.trace("reversing linked package record creation %s", self.target_full_path)
        # TODO: be careful about failure here, and being too strict
        PrefixData(self.target_prefix).remove(self.package_info.repodata_record.name)


class UpdateHistoryAction(CreateInPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, target_prefix, remove_specs, update_specs):
        target_short_path = join('conda-meta', 'history')
        return cls(transaction_context, target_prefix, target_short_path,
                   remove_specs, update_specs),

    def __init__(self, transaction_context, target_prefix, target_short_path, remove_specs,
                 update_specs):
        super(UpdateHistoryAction, self).__init__(transaction_context, None, None, None,
                                                  target_prefix, target_short_path)
        self.remove_specs = remove_specs
        self.update_specs = update_specs

        self.hold_path = self.target_full_path + '.c~'

    def execute(self):
        log.trace("updating environment history %s", self.target_full_path)

        if lexists(self.target_full_path):
            copy(self.target_full_path, self.hold_path)

        h = History(self.target_prefix)
        h.update()
        h.write_specs(self.remove_specs, self.update_specs)

    def reverse(self):
        if lexists(self.hold_path):
            log.trace("moving %s => %s", self.hold_path, self.target_full_path)
            backoff_rename(self.hold_path, self.target_full_path, force=True)

    def cleanup(self):
        rm_rf(self.hold_path)


class RegisterEnvironmentLocationAction(PathAction):

    def __init__(self, transaction_context, target_prefix):
        self.transaction_context = transaction_context
        self.target_prefix = target_prefix

        self._execute_successful = False

    def verify(self):
        touch(USER_ENVIRONMENTS_TXT_FILE, mkdir=True, sudo_safe=True)
        self._verified = True

    def execute(self):
        log.trace("registering environment in catalog %s", self.target_prefix)

        register_env(self.target_prefix)
        self._execute_successful = True

    def reverse(self):
        pass

    def cleanup(self):
        pass

    @property
    def target_full_path(self):
        raise NotImplementedError()


# ######################################################
#  Removal of Paths within a Prefix
# ######################################################

@with_metaclass(ABCMeta)
class RemoveFromPrefixPathAction(PrefixPathAction):

    def __init__(self, transaction_context, linked_package_data, target_prefix, target_short_path):
        super(RemoveFromPrefixPathAction, self).__init__(transaction_context,
                                                         target_prefix, target_short_path)
        self.linked_package_data = linked_package_data

    def verify(self):
        # inability to remove will trigger a rollback
        # can't definitely know if path can be removed until it's attempted and failed
        self._verified = True


class UnlinkPathAction(RemoveFromPrefixPathAction):
    def __init__(self, transaction_context, linked_package_data, target_prefix, target_short_path,
                 link_type=LinkType.hardlink):
        super(UnlinkPathAction, self).__init__(transaction_context, linked_package_data,
                                               target_prefix, target_short_path)
        conda_temp_extension = '.c~'
        self.holding_short_path = self.target_short_path + conda_temp_extension
        self.holding_full_path = self.target_full_path + conda_temp_extension
        self.link_type = link_type

    def execute(self):
        if self.link_type != LinkType.directory:
            log.trace("renaming %s => %s", self.target_short_path, self.holding_short_path)
            backoff_rename(self.target_full_path, self.holding_full_path, force=True)

    def reverse(self):
        if self.link_type != LinkType.directory and lexists(self.holding_full_path):
            log.trace("reversing rename %s => %s", self.holding_short_path, self.target_short_path)
            backoff_rename(self.holding_full_path, self.target_full_path, force=True)

    def cleanup(self):
        if self.link_type == LinkType.directory:
            try_rmdir_all_empty(self.target_full_path)
        else:
            rm_rf(self.holding_full_path)


class RemoveMenuAction(RemoveFromPrefixPathAction):

    @classmethod
    def create_actions(cls, transaction_context, linked_package_data, target_prefix):
        if on_win:
            MENU_RE = re.compile(r'^menu/.*\.json$', re.IGNORECASE)
            return tuple(cls(transaction_context, linked_package_data, target_prefix, trgt)
                         for trgt in linked_package_data.files if bool(MENU_RE.match(trgt)))
        else:
            return ()

    def __init__(self, transaction_context, linked_package_data,
                 target_prefix, target_short_path):
        super(RemoveMenuAction, self).__init__(transaction_context, linked_package_data,
                                               target_prefix, target_short_path)

    def execute(self):
        log.trace("removing menu for %s ", self.target_prefix)
        make_menu(self.target_prefix, self.target_short_path, remove=True)

    def reverse(self):
        log.trace("re-creating menu for %s ", self.target_prefix)
        make_menu(self.target_prefix, self.target_short_path, remove=False)

    def cleanup(self):
        pass


class RemoveLinkedPackageRecordAction(UnlinkPathAction):

    def __init__(self, transaction_context, linked_package_data, target_prefix, target_short_path):
        super(RemoveLinkedPackageRecordAction, self).__init__(transaction_context,
                                                              linked_package_data,
                                                              target_prefix, target_short_path)

    def execute(self):
        super(RemoveLinkedPackageRecordAction, self).execute()
        PrefixData(self.target_prefix).remove(self.linked_package_data.name)

    def reverse(self):
        super(RemoveLinkedPackageRecordAction, self).reverse()
        PrefixData(self.target_prefix)._load_single_record(self.target_full_path)


class UnregisterEnvironmentLocationAction(PathAction):

    def __init__(self, transaction_context, target_prefix):
        self.transaction_context = transaction_context
        self.target_prefix = target_prefix

        self._execute_successful = False

    def verify(self):
        self._verified = True

    def execute(self):
        log.trace("unregistering environment in catalog %s", self.target_prefix)

        unregister_env(self.target_prefix)
        self._execute_successful = True

    def reverse(self):
        pass

    def cleanup(self):
        pass

    @property
    def target_full_path(self):
        raise NotImplementedError()


# ######################################################
#  Fetch / Extract Actions
# ######################################################

class CacheUrlAction(PathAction):

    def __init__(self, url, target_pkgs_dir, target_package_basename,
                 md5sum=None, expected_size_in_bytes=None):
        self.url = url
        self.target_pkgs_dir = target_pkgs_dir
        self.target_package_basename = target_package_basename
        self.md5sum = md5sum
        self.expected_size_in_bytes = expected_size_in_bytes
        self.hold_path = self.target_full_path + '.c~'

    def verify(self):
        assert '::' not in self.url
        self._verified = True

    def execute(self, progress_update_callback=None):
        # I hate inline imports, but I guess it's ok since we're importing from the conda.core
        # The alternative is passing the PackageCache class to CacheUrlAction __init__
        from .package_cache_data import PackageCacheData
        target_package_cache = PackageCacheData(self.target_pkgs_dir)

        log.trace("caching url %s => %s", self.url, self.target_full_path)

        if lexists(self.hold_path):
            rm_rf(self.hold_path)

        if lexists(self.target_full_path):
            if self.url.startswith('file:/') and self.url == path_to_url(self.target_full_path):
                # the source and destination are the same file, so we're done
                return
            else:
                backoff_rename(self.target_full_path, self.hold_path, force=True)

        if self.url.startswith('file:/'):
            source_path = unquote(url_to_path(self.url))
            if dirname(source_path) in context.pkgs_dirs:
                # if url points to another package cache, link to the writable cache
                create_hard_link_or_copy(source_path, self.target_full_path)
                source_package_cache = PackageCacheData(dirname(source_path))

                # the package is already in a cache, so it came from a remote url somewhere;
                #   make sure that remote url is the most recent url in the
                #   writable cache urls.txt
                origin_url = source_package_cache._urls_data.get_url(self.target_package_basename)
                if origin_url and has_platform(origin_url, context.known_subdirs):
                    target_package_cache._urls_data.add_url(origin_url)
            else:
                # so our tarball source isn't a package cache, but that doesn't mean it's not
                #   in another package cache somewhere
                # let's try to find the actual, remote source url by matching md5sums, and then
                #   record that url as the remote source url in urls.txt
                # we do the search part of this operation before the create_link so that we
                #   don't md5sum-match the file created by 'create_link'
                # there is no point in looking for the tarball in the cache that we are writing
                #   this file into because we have already removed the previous file if there was
                #   any. This also makes sure that we ignore the md5sum of a possible extracted
                #   directory that might exist in this cache because we are going to overwrite it
                #   anyway when we extract the tarball.
                source_md5sum = compute_md5sum(source_path)
                exclude_caches = self.target_pkgs_dir,
                pc_entry = PackageCacheData.tarball_file_in_cache(source_path, source_md5sum,
                                                                  exclude_caches=exclude_caches)

                if pc_entry:
                    origin_url = target_package_cache._urls_data.get_url(
                        pc_entry.extracted_package_dir
                    )
                else:
                    origin_url = None

                # copy the tarball to the writable cache
                create_link(source_path, self.target_full_path, link_type=LinkType.copy,
                            force=context.force)

                if origin_url and has_platform(origin_url, context.known_subdirs):
                    target_package_cache._urls_data.add_url(origin_url)
                else:
                    target_package_cache._urls_data.add_url(self.url)

        else:
            download(self.url, self.target_full_path, self.md5sum,
                     progress_update_callback=progress_update_callback)
            target_package_cache._urls_data.add_url(self.url)

    def reverse(self):
        if lexists(self.hold_path):
            log.trace("moving %s => %s", self.hold_path, self.target_full_path)
            backoff_rename(self.hold_path, self.target_full_path, force=True)

    def cleanup(self):
        rm_rf(self.hold_path)

    @property
    def target_full_path(self):
        return join(self.target_pkgs_dir, self.target_package_basename)

    def __str__(self):
        return 'CacheUrlAction<url=%r, target_full_path=%r>' % (self.url, self.target_full_path)


class ExtractPackageAction(PathAction):

    def __init__(self, source_full_path, target_pkgs_dir, target_extracted_dirname,
                 record_or_spec, md5sum):
        self.source_full_path = source_full_path
        self.target_pkgs_dir = target_pkgs_dir
        self.target_extracted_dirname = target_extracted_dirname
        self.hold_path = self.target_full_path + '.c~'
        self.record_or_spec = record_or_spec
        self.md5sum = md5sum

    def verify(self):
        self._verified = True

    def execute(self, progress_update_callback=None):
        # I hate inline imports, but I guess it's ok since we're importing from the conda.core
        # The alternative is passing the the classes to ExtractPackageAction __init__
        from .package_cache_data import PackageCacheData
        log.trace("extracting %s => %s", self.source_full_path, self.target_full_path)

        if lexists(self.hold_path):
            rm_rf(self.hold_path)
        if lexists(self.target_full_path):
            try:
                backoff_rename(self.target_full_path, self.hold_path)
            except (IOError, OSError) as e:
                if e.errno == EXDEV:
                    # OSError(18, 'Invalid cross-device link')
                    # https://github.com/docker/docker/issues/25409
                    # ignore, but we won't be able to roll back
                    log.debug("Invalid cross-device link on rename %s => %s",
                              self.target_full_path, self.hold_path)
                    rm_rf(self.target_full_path)
                else:
                    raise

        extract_tarball(self.source_full_path, self.target_full_path,
                        progress_update_callback=progress_update_callback)

        raw_index_json = read_index_json(self.target_full_path)

        if isinstance(self.record_or_spec, MatchSpec):
            url = self.record_or_spec.get_raw_value('url')
            assert url
            channel = Channel(url) if has_platform(url, context.known_subdirs) else Channel(None)
            fn = basename(url)
            md5 = self.md5sum or compute_md5sum(self.source_full_path)
            repodata_record = PackageRecord.from_objects(raw_index_json, url=url,
                                                         channel=channel, fn=fn, md5=md5)
        else:
            repodata_record = PackageRecord.from_objects(self.record_or_spec, raw_index_json)

        repodata_record_path = join(self.target_full_path, 'info', 'repodata_record.json')
        write_as_json_to_file(repodata_record_path, repodata_record)

        target_package_cache = PackageCacheData(self.target_pkgs_dir)
        package_cache_record = PackageCacheRecord.from_objects(
            repodata_record,
            package_tarball_full_path=self.source_full_path,
            extracted_package_dir=self.target_full_path,
        )
        target_package_cache.insert(package_cache_record)

        # dist = Dist(recorded_url) if recorded_url else Dist(path_to_url(self.source_full_path))
        # package_cache_entry = PackageCacheRecord.make_legacy(self.target_pkgs_dir, dist)
        # target_package_cache[package_cache_entry.dist] = package_cache_entry

    def reverse(self):
        rm_rf(self.target_full_path)
        if lexists(self.hold_path):
            log.trace("moving %s => %s", self.hold_path, self.target_full_path)
            rm_rf(self.target_full_path)
            backoff_rename(self.hold_path, self.target_full_path)

    def cleanup(self):
        rm_rf(self.hold_path)

    @property
    def target_full_path(self):
        return join(self.target_pkgs_dir, self.target_extracted_dirname)

    def __str__(self):
        return ('ExtractPackageAction<source_full_path=%r, target_full_path=%r>'
                % (self.source_full_path, self.target_full_path))
